An example of the state of the art air gun is disclosed in U.S. Pat. No. 5,205,271 issued to the present inventor. The invention consists of a fork-shaped piece that is hinged on the barrel and that is secured to the compression chamber. A plastic casing is molded on the barrel, with a back part thereof pivotally hinged with a fork member that is also molded plastic. A rearward extension is integral with the front part of the compression chamber, and there is an axial passage extending through the rearward extension for the passage of the compressed air.
Additionally, prior art metallic pistons comprise a lengthwise slot serving for the connection of the thrusting means, designed to compress the piston spring, and for the inclusion of the safety catch associated to the trigger, which locks the piston at a spring compressed position. The slot sustains significant friction and impacts so it is characterized by its great resistance to wear.
To cut the piston cost, attempts have been made in producing a piston in plastic material incorporating a recess for the thrusting means and the safety catch. But even the harder plastic materials (regardless of their high cost that is incompatible with the aim sought) did not resist the stresses due to the repeated action of the thrusting element and the safety catch.